The present invention relates to a semiconductor integrated device which enables low-voltage driving, high speed and high integration in a semiconductor integrated circuit. This invention relates also to a method of detecting a voltage drop of the integrated circuit and a method of correcting the voltage drop.
As computerization has been improved in recent years, the integration degree of integrated circuits has been heightened every year. Meanwhile, a driving voltage of the integrated circuit is being lowered to 2.5 V or 1.8 V in order to cope with energy conservation and mobilization.
As the density of the integrated circuit is heightened, power-supply wiring on the integrated circuit has become narrower. This is disadvantageous for supplying a power source due to an increase of resistance. Meanwhile, power consumption increases due to a high-speed operation, and a lot of transistors are actuated. As a result, a voltage drop easily occurs when an electrical current is supplied to the integrated circuit.
As a general technique which copes with the voltage drop, there exists a microcomputer disclosed in Japanese Patent Application Laid-Open No. 7-56885. When the power-supply voltage drops or the frequency of a system clock becomes high reaching an operational limit, this microcomputer detects this state and changes a sense amplification circuit having a plurality of circuit constants secure a suitable operational range according to the power-supply voltage or changes the frequency of the system clock.
When the voltage drop becomes greater in the integrated circuit, the transistors in the integrated circuit cannot operate normally, and normal operation of the whole integrated circuit cannot be ensured. Particularly, this phenomenon that the normal operation cannot be ensured easily occurs in low-voltage driving, and seriously interfering with low-voltage driving, high speed and high integration of the integrated circuit.
It is an object of the invention to provide a semiconductor integrated device detecting a voltage drop of a power-supply voltage in an integrated circuit and correcting the voltage drop and to provide a method of detecting a voltage drop of an integrated circuit and a method of correcting a voltage drop.
According to a semiconductor integrated device of one aspect of the present invention, the voltage detection cell is arranged in the predetermined position on the power-supply wiring in the semiconductor integrated circuit and detects a power-supply voltage in the predetermined position. The power-supply voltage is output to the voltage drop detection circuit via the connection wiring, and the voltage drop detection circuit detects a voltage drop of the power-supply voltage detected by the voltage detection cell.
Further, the voltage drop detection circuit is composed of the comparator and compares the power-supply voltage detected by the voltage detection cell with a reference voltage. A judgment is made based on the compared result as to whether or not a voltage drop occurs.
Further, the delay element in the voltage drop detection circuit delays and output a predetermined input signal according to a voltage drop of the power-supply voltage detected by the voltage detection cell. The flip-flop circuit judges as to whether or not a voltage drop amount is not less than a predetermined value based on the predetermined input signal and the signal delayed and output by the delay element and outputs the judged result.
Further, the voltage drop correction circuit corrects the voltage drop of the power-supply voltage based on the voltage drop which is detected by the voltage drop detection circuit.
Further, the voltage drop correction circuit is a frequency control circuit. The frequency control circuit changes a clock frequency of the power-supply voltage based on the voltage drop detected by the voltage drop detection circuit, and corrects the voltage drop.
Further, the voltage drop correction circuit is a voltage control circuit. The voltage control circuit changes a voltage of the power-supply voltage based on the voltage drop detected by the voltage drop detection circuit, and corrects the voltage drop.
According to the method of detecting a voltage drop in an integrated circuit of another aspect of this invention, the cell arrangement determination step determines a predetermined position of the voltage detection cell which is arranged in the predetermined position on the power-supply wiring in the semiconductor integrated circuit and detects a power-supply voltage in the predetermined position. The wiring position determination step determines a wiring position of the connection wiring for connecting the voltage detection cell and the voltage drop detection circuit for detecting the voltage drop of the power-supply voltage detected by the voltage detection cell. The integrated circuit producing step produces the integrated circuit including the voltage detection cell and the connection wiring. The voltage drop detection step detects the voltage drop of the power-supply voltage detected by the voltage detection cell using the voltage drop detection circuit.
Further, the voltage drop detection step compares the voltage detected by the voltage detection cell with a reference voltage and detects the voltage drop of the power-supply voltage based on the compared result.
Further, the voltage drop detection step detects a voltage drop of the power-supply voltage based on the delay amount according to the voltage detected by the voltage detection cell.
According to method of correcting a voltage drop in an integrated circuit of still another aspect of the present invention, the cell arrangement determination step determines a predetermined position of the voltage detection cell which is arranged in the predetermined position on the power-supply wiring in the semiconductor integrated circuit and detects the power-supply voltage in the predetermined position. The wiring position determination step determines a wiring position of the connection wiring for connecting the voltage detection cell and the voltage drop detection circuit for detecting the voltage drop of the power-supply voltage detected by the voltage detection cell. The integrated circuit production step produces an integrated circuit including the voltage detection cell and the connection wiring. The voltage drop detection step detects the voltage drop of the power-supply voltage detected by the voltage detection cell by means of the voltage drop detection circuit. The voltage drop correction step corrects the voltage drop of the power-supply voltage based on the voltage drop detected at the voltage drop detection step.
Further, the voltage drop correction step changes a clock frequency of the power-supply voltage based on the voltage drop detected at the voltage drop detection step so as to correct the voltage drop.
Further, the voltage drop correction step changes a voltage of the power-supply voltage based on the voltage drop detected at the voltage drop detection step so as to correct the voltage drop. As a result, low voltage and the high speed in the semiconductor integrated circuit are ensured, and the reliability can be heightened.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.